The present invention pertains to a compressed air landing strut which contains the following components:
a pneumatic shock absorber with rolling bellows which enclose a spring space
a roll-off piston along which the rolling bellows can roll
a spring support that is immersed in the roll-off piston, with an offset in which the roll-off piston is braced
a ring-shaped gasket which is located between the spring support and the roll-off piston and seals the spring space against the environment.
A compressed air landing strut of the kind specified above is known, for example, from German 44 28 601 A1. The compressed air landing strut contains a pneumatic shock absorber with an outer tube which, together with a rolling bellows and a roll-off piston, surrounds a spring space. The roll-off piston of the pneumatic shock absorber is braced on an offset of the spring support, which can be designed, for example, as a shock absorber. Above the offset of the spring support there is a groove in the inner wall of the roll-off piston, in which a ring-shaped gasket is installed between the spring support and the roll-off piston, which seals the spring space surrounded by the pneumatic shock absorber air tight against the environment.
German 44 28 601 A1 does not indicate specifically how the sealing is established between the spring support and the roll-off piston. However, from German 195 22 459 C1 by the same applicant, it is known how to make the ring-shaped groove between the spring support and the roll-off piston accessible from outside the roll-off piston to fill it with a shapeable sealing material from the outside via an injection opening, which rests on one side against the roll-off piston and on the other side against the spring support.
The compressed air landing strut known from German 44 28 601 A1 and from German 195 22 459 C1 has a dependable sealing of the pneumatic shock absorber against the environment. However, it is evident that the compressed air landing strut known from the aforementioned publications must first be fully assembled; the seal between the spring support and the roll-off piston can only be established thereafter. To this extent, the manufacturing method of the compressed air landing strut according to German 44 28 601 A1 or according to German 195 22 459 C1 can be considered to be complicated.
From DE 195 08 980 C1 is known a compressed air landing strut with a pneumatic shock absorber whose roll-off piston is braced in a tumbler movement against a telescoping shock absorber. To do this, a flange-like collar is set onto the outer tube of the telescoping shock absorber, on which a ring part of elastomer material is placed. The end region of the roll-off piston facing the outer tube of the telescoping shock absorber is likewise designed as a flange-like collar, and is set onto the elastomer ring part. The collars preferably have the shape of a spherical segment.
Due to the explained attachment of the roll-off piston to the outer tube of the telescoping shock absorber, a tumbler movement of the roll-off piston is ensured. However, we find that to ensure this tumbler movement, the flange-like collar must have a significantly larger diameter than the outer tube of the telescoping shock absorber. In order to avoid an adverse impact on the axial stability of the outer tube of the telescoping shock absorber, the flange-like collar is thus designed as a separate component. This requires a separate sealing of the flange-like collar against the environment. In addition, the ring part must have a complicated shape in order to ensure sufficient sealing of the spherical-segment-shaped collar. It is thus expensive to manufacture. For the reasons stated above, the attachment of the pneumatic shock absorber to a spring support known from German 195 08 980 C1 has only limited applicability.
It is therefore an object of the invention to create an attachment of a pneumatic shock absorber to a spring support which is easy to manufacture and which will ensure a reliable sealing of the space enclosed by the pneumatic shock absorber against the environment.
The above and other objects of the present invention can be achieved by a compressed air landing strut which contains the following components:
a pneumatic shock absorber with a rolling bellows which encloses a spring space,
a roll-off piston along which the rolling bellows can roll,
a spring support that is plunged into the roll-off piston, with an offset in which the roll-off piston is braced,
a ring-shaped gasket which is located between the spring support and the roll-off piston, and seals the spring space against the environment,
and where on the offset of the spring support there is an O-ring whose cross sectional surface diameter is sized so that it covers at least the width of the offset, and further that
the end region of the roll-off piston facing the spring support is flared radially outward, and that
the spring support is plunged into the roll-off piston in such a manner that the end region of the roll-off piston, flared radially outward, surrounds the offset of the spring support, and the O-ring is compressed radially between the outer wall of the spring support and the inner wall of the end region of the roll-off piston.
Preferably, the cross-sectional surface diameter of the O-ring in the unstressed state of the O-ring is greater than the width of the offset, in order to ensure a good radial compression of the O-ring. Typically, the cross-sectional surface of the O-ring (i.e., the cord thickness) will have a diameter of 2 mm to 8 mm and the width of the offset amounts to about 60% to 80% of the selected cord thickness (at a cord thickness of 5 mm, the width of the offset is thus 3 mm to 4 mm, so that the O-ring will be compressed radially by 1 mm to 2 mm).